Pumps for the transport of gases or for the creation of a vacuum exist in macroscopic scale in a number of type variations: displacement pumps, molecular pumps, sorption pumps, condensors, kyro pumps and driving agent pumps. Each of these varieties is suited for application within a specific pressure region; to create a pregiven pressure it can be necessary to operate a number of these pumps in series. The sizes of these customary vacuum pumps even in their smallest construction forms lie in the area of several tens of cubic centimeters. Therefore these pumps cannot be sensibly integrated into systems with microcomponents (for example, sensors). The application of, for example, miniaturized analysis devices, which for their function require a vacuum pressure or a constant gas flow is therefore closely coupled to the development of suitable micro gas pumps.
Micropumps use different physical or chemical principles to create a pumping effect (see, for example: Nam-Trung Nguyen, Xiaoyang Huang, Toh Kok Chuan, MEMS-Micropumps: A Review, Transactions of the ASME, Vol. 124 (June 2002), 384-392; P. Woias, Micropumps—summarizing the first two decades, Proc. SPIE, Vol. 4560 (2001), 39-52). Many of the systems are limited in their application to liquid medium; only a few suit themselves to the pumping of gases or to the creation of a vacuum.
A scaling of the customary pump principles with rotating parts for the displacement of gases is, because of the very small measures and the required rotational speeds for the creation of the displacement, nearly impossible. Most of the realized microvacuum pumps are based however on mechanically movable parts which considerably influence the long time stability of such systems, such as membranes, which through their movement create by way of different actuators the evoked pumping effect or in part require active or passive valves (see, for example: R. Rapp, W. K. Schomburg, D. Mass, J. Schulz, W. Stark, LIGA micropump for gases and liquids, Sens. Act. A. Vol. 40 (January 1994), 57-61; R. Linnemann, P. Wias-P, C. D. Senfft, J. A. Ditte rich, A self-priming and bubble-tolerant piezoelectric silicon micropump for liquids and gases, Proc. MEMS 1998 Heidelberg, 532-537; C. G. J. Schabmueller, M. Koch, A. G. R. Evans, A. Brunnschweiler, M. Kraft, Design and fabrication of a self-aligning gas/liquid micropump, Proc. SPIE-Int. Soc. Opt. Eng. (USA), Vol. 4177 (2000), 282-90).
Also capable of finding application are alternative pumps without mechanical parts and which are based on the principle of Knudsen compressors (thermal transpiration, thermal molecular pressure): between the two volumes at different temperatures which are connected to one another by way of a channel with a small cross sectional area, there exists a pressure difference which can be used for the creation of a pumping effect. Disadvantageous of this however is the relatively complicated construction and the high surface area requirement of such systems, indeed because of the low achievable compression ratio, many such pumps need to be driven in a series in order to create the desired suction performance and pressure difference (see, for example: R. M. Young, Analysis of a micromachine based vacuum pump on a chip actuated by thermal transpiration effect, J. Vac. Sci. Technol B 17(2), March/April 1999; J. P. Hobson, D. B. Salzman, Review of pumping by thermal molecular pressure, J. Vac. Sci. Technol. A 18(4), July/August 2000, S. E. Vargo, E. P. Muntz, Initial Results from the first MEMS fabricated thermal transpiration-driven vacuum pump, Rerefied Gas Dynamics: 22. Int. Symposium, 2001).
The use of the pumping principle forming the basis of the invention is not known in micropumps.